Examensarbeten på grundnivå


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    Utvärdering av analysmetoder för detektering av mikrober.
    (2020) Sehdo, Sara; Chalmers tekniska högskola / Institutionen för biologi och bioteknik; Larsson, Christer; Olsson, Yvonne
    Surface coatings are widely used both by individuals and companies. To avoid problems such as bacterial growth, which will result in the disposal of the coating, a need to monitor the growth arises. The focus of this study is comparing three different methods to detect microorganisms, two of the ATP-detection versions (LuciPac and QG21S) and one with culturing microbes, where three different agar media are used. Before evaluating the methods, an inoculum had to be composed using wastewater from production. The goal is to reach an understanding regarding which of these are the best to use depending on the user’s objective. The result of the paper is that depending on the economic situation the preferred method will differ. Agar is recommended to always be used as it can detect spores which the ATP-methods cannot, thus making it a necessity in contaminationdetection, though it takes at least 24h getting a result. Both ATP-methods takes about 5-10 minutes before receiving a result. While LuciPac is the cheaper version of ATP-detection it is also lacking in detecting all the ATP in samples and cannot be used with pigmented coatings. However, as QG21S is a thorough method it is expensive, hence recommended to be used sparingly. It can also detect microbes in pigmented coatings and should therefore be use with those. This report is written in Swedish. English title: "Evaluation of analytical methods for detection of microbes".
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    Undersökning av variabler vid optimering av syrningsprocessen för framställning av cottage cheese
    (2019) Hansson, Björn; Chalmers tekniska högskola / Institutionen för biologi och bioteknik; Chalmers University of Technology / Department of Biology and Biological Engineering
    Arla Foods dairy in Falkenberg produces cottage cheese and under the fall of 2018, they had some problems with an uneven acidification, which gave their product an uneven quality. Those problems are now solved but in the continued work their product technicians always work to find methods for a more reliable and stable acidification process, for a product with more even quality. In the work for a more reliable and stable process, two projects have been done. The acidification project performed to examine which conditions that were most optimal regarding the temperature, the percentage of protein in the milk and the amount of starter culture used. The other project, the vat and cooling towers project, was done to examine the change in dry matter content in the cheese curd when there are delays in the production line, i.e. when the cheese curd has to lie in the vat longer than usual and how that affects the curds dry matter content, and how long the curd has to lie in the cooling towers to reach normal dry matter content limits. Both projects were done in laboratory scale. In the acidification project the rate of the acidification were assessed by measuring the pH of the sample every fifteen minutes. The times down to pH 5.7 (when rennet is added) and pH 4.7 (when the coagulum is cut) were measured and used to calculate the results using a 2 sided 95 % confidence interval. The temperature, the percentage of the milk and their factor interaction were significant for the rate of acidification down to pH 5.7. For the acidification rate down to pH 4.7, all the factors and factor interactions were significant except for the three-way factor interaction. A higher temperature made the acidification rate increase while a higher percentage of protein in the milk decreased the acidification rate. In the vat and cooling towers project whey and cheese curd were stirred and heated at 60 ℃ in a beaker, with samples of the curd taken out after 0, 30, 60 and 90 minutes. At these times cheese curd was transferred to a stirred and cooled beaker with 4 ℃ water in them, with samples of the curd taken out after 2, 4 and 6 hours. The dry matter of the cheese curd was then measured with a Milkoscan FT1. Because of the different chemical compositions of the cheese curd taken out from different vats the results were not comparable but a significant drop in dry matter could be seen from all runs after two hours of cooling.
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    B cells maturation in infancy and its affect in early allergy
    (2019) Karlsson, Emma; Chalmers tekniska högskola / Institutionen för biologi och bioteknik; Chalmers University of Technology / Department of Biology and Biological Engineering
    The last decades, the presence of allergy has increased in countries belonging to the Western world and over 25 % of Swedish young people are affected of allergic symptoms. One reasonable explanation is the hygiene hypothesis, mentioned by David Strachan 1989, that associate the increase in allergy development with a cleaner lifestyle. Previous studies showed that children who grew up on a farm with animals had a more maturated immune system and therefore developed less allergy. With samples received from the study named Nutritional impact on Immunological maturation during Childhood in relation to the Environment(NICE),I have studied the B cells maturation during early time in life. By studying subpopulations of B cells, specific surface markers are stained with fluorochromes to be analysed with a flow cytometer. Thus, the development of B cell subpopulations from birth up to 4 months can be charted. Several surface markers can indicate the same subpopulation, i.e. CD27+ and CD24hiCD38lo that are expressed by memory B cells. However, the percentage differ from each other and the most liable reason is that the surface markers have different functions in the B cells, and are therefore not only expressed during one phase of the development of B cells. My results shows that the development of percentage of subpopulations of B cells differ from each other from birth up to 4 months. Correlation tests indicate that CD27+ and CD24hiCD38lo could both be used to detect memory B cells. Correlation tests at number of subpopulations had higher correlation coefficient and were strongly significant at birth. Therefore, it would be interesting to continue the analysis of numbers of B cells populations at 48h, 1, 4 and 12 months of life. In the NICE study, so far 452 children have been examined for allergy and 6.2 % suffered from eczema, 2.4 % of food allergy and 6.2 % of the children had developed asthmaat1yearofage. Inthisthesis, there was no significant associations between B cell maturity and the development of allergy.
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    Analysis of avenanthramides in oats with Ultra High Performance Liquid Chromatography
    (2016) Astner, Martin; Chalmers tekniska högskola / Institutionen för biologi och bioteknik; Chalmers University of Technology / Department of Biology and Biological Engineering
    Avenanthramides have been shown to have beneficial properties such as strong antioxidant activity and anti-inflammatory effects in humans, and are a key defence molecule for oats. The goal of this project was to create and validate a method for quantification of avenanthramides in oats that would take less than 20 minutes. A new extraction method and new liquid chromatography method were tested, as well as the introduction of an internal standard to improve quantification. We found that the internal standard selected was not stable during extraction and that it was necessary to use an external standard curve. We found that the liquid chromatography method was reproducible for standard compounds and that we could get separation of the three main avenathramides in oats for a total run time of 15 minutes. The extraction component of the method requires further work to improve recovery and stability before this method can be used for quantification of avenanthramides in oats.
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    Optimering av en gaskromatografisk tandem-masspektrometrisk metabolomikmetod för cerebrospinalvästska med tillämpning relaterat till Alzheimers sjukdom
    (2016) Vänerlöv, Xuan; Chalmers tekniska högskola / Institutionen för biologi och bioteknik; Chalmers University of Technology / Department of Biology and Biological Engineering
    I detta experiment har gaskromatografi använts för att separera analyterna i cerebrospinalvätska och sedan har masspektrometri används innehållande en trippel kvadrupol som körts i MRM-läge parallellt med fullt skanningsläge. För att Multiple Reaction Monitoring MRM skulle kunna användas var parametrar tvungna att optimeras från de standarderna som sedan skulle analyseras i provet. Standarderna som optimerades var ett urval metaboliter till en metod relaterat till diabetes samt hjärnans signalsubstanser dopamin, serotonin, epinefrin, gamma-aminobutyric acid (GABA) och acetylkolin. Metoden som användes var en befintlig metod utformad för plasmaprover som modifierades för att passa cerebrospinalvätska. Den modifierade metoden med de tillagda substanserna testades och utvärderades sedan. Dopamin, serotonin, GABA och epinefrin kunde optimeras för MRM-läge och dopamin och GABA kunde ses i cerebrospinalvätska. Vid utvärdering av metoden hade majoriteten av metaboliterna tillräckligt hög reproducerbarhet för att inkluderas i metoden. Slutsatsen som drogs var att gaskromatografi med en masspektrometer innehållande en trippel kvadrupol var lämplig till metoden för cerebrospinalvätska. Metoden kan appliceras vid undersökning av olika sjukdomar som till exempel Alzheimers sjukdom och tas därför upp som ett omfattande kapitel i rapporten.